Trying to nail down a specific, up-to-the-minute ebook release for an author like Chan Ho-kei can be a bit like chasing ghosts. Official channels are your safest bet, but his mainland Chinese publisher often has the earliest digital editions. Sites like Dangdang or JD.com for simplified Chinese versions are worth checking regularly.
That said, international platforms like Amazon Kindle or Google Play Books might eventually list them, but the lag can be significant, sometimes months. If you read traditional Chinese, the Taiwanese publisher's site could be another route, though their release schedule differs.
Honestly, following the author's official social media, if he has any, or the publisher's announcements is the most reliable method. I just wish the digital distribution for these intricate crime novels was as streamlined as the plots themselves.
The wait for a new 'Inspector Kwan' installment always feels longer than it probably is, but spotting that new listing pop up online is its own little reward.